Fading Star
by BrightWings111
Summary: Hoshiko Tsukino is Aizen's lab rat. The tests are painful, but he gives her a power that could kill him if she wants to. When he departs from Soul Society for Hueco Mundo, Unohana saves her from being taken with him. After Squad placement and seat placement, she trains hard to settle her score with Aizen. With the help of our favorite chibi of course. ToshiroxOC
1. Chapter 1

**Brighty: I've been dying to write this for a while so…**

**Hoshiko: Brighty doesn't own Bleach, Tite Kubo does. She only owns me**

**Brighty: Thank you for doing the disclaimer**

**Hoshiko: Just get on with it**

A test subject. An experiment. That's all I am. He keeps me locked away until he decides to run a new test. When that time comes, he brings me to a dark place where he hooks me and my zanpaku-to up to strange machines. Not one test has ever gone by that hasn't made me scream in agony.

I know he's dangerous. I know he means to harm Soul Society. But I can't go against him. I can't tell anyone. The last time I showed a hint of rebellion, which was a simple 'please stop' cried out during a test, he tortured me so much that my throat was dry from screaming. If I told anyone, a single soul, my life would become even more of a hell than it already is.

My name is Hoshiko Tsukino. My job is to be Captain Sosuke Aizen's lab rat. I don't know what those machines do to me and my zanpaku-to. I do know that they hurt, and he does that intentionally. Most of the time, my only friend is my zanpaku-to. Toketsu Yoru is his name. He looks like a normal jet black wolf. I usually keep my will to live because he helps me.

I'm hooked up to the machine now, gritting through the pain. _Hold on, Hoshi._ His voice rings through my head. I know Toketsu Yoru is going through as much pain, if not more than I am right now.

_You hold on too,_ I reply. _We'll get through another day._

"Good job, Hoshiko," Aizen says when the machine stops whirring. But he doesn't unhook me from the machine. "Now we'll try something new."

Someone walks into the test room. I can't tell who it is. I doubt I would know who it is even if I could see their face. I grit my teeth and nod.

Aizen attaches the mystery person's zanpaku-to up to the machine, and then starts it. It hurts more than all of the other tests combined. The only way I can explain this damn machine is to pretend my spiritual pressure is like a block of ice. Usually, it feels like someone is slicing the ice open and analyzing it, then freezing it back together. But not today. Today it feels like they're completely melting it, adding something unknown to it, and then refreezing it again. It hurts; it hurts so much I wish that I wish Aizen would just kill me already and stop this pain. I know he's just testing on me and planning to kill me later. I just want this pain to stop.

The minutes feel like years. Once I start to somewhat get used to the level of pain I'm in, it starts hurting more. There's no end to it. I nearly cry for joy when the machine stops, but I'm already crying from the pain.

"I think that was a successful test," Aizen says. He unhooks the other person's zanpaku-to first, then that other person leaves. I realize I still don't know who it is.

"Please," I risk a whimper. "At least tell me what you did to me."

"I was planning on telling you," Aizen says. "What I've just done is give you his power."

"W-what do you mean," I stutter. My voice seems incapable of reaching above a whisper.

"You'll find out soon enough." He looks smug and overconfident. I want to just reach out and smack him. I almost smack myself for having such a thought. If I did that, I don't want to think about what he'd do to me. It would probably be worth the satisfaction of slapping him, though.

He unhooks me and Toketsu Yoru from the machine and throws us back in my room. I grab my zanpaku-to and immediately connect with him to see how he feels.

My "inner world" where I converse with him is dark. It's really almost the equivalent to nothing. It's open tundra, with no landmarks or light. It's always night there.

_Toketsu Yoru!_ I call out to him. _Are you okay?_ I don't see him. Where could he be? It's nothing but open space for goodness sake!

_Here._ He sounds exhausted. I can barely hear him. I now realize why I can't see him. He's collapsed on his side from pain and exhaustion.

_Toketsu Yoru!_ I call out of worry. I run over to him, only to freeze at what I see. He's not just a plain black wolf anymore. Somehow, Aizen had put black bat wings on him. _What did he do to you?_

_I don't know,_ he grunts. He sounds really worn out. _But it hurts like hell._ I help him stand up, but he falls back down. We settle with just getting him into a more comfortable position lying down, not on his side the way he was.

I trace a finger down the base of one of his wings. He yelps in pain. _I'm sorry!_ I gasp.

_Don't be,_ he mutters. _None of this is your fault._ He tries moving his wings, and winces in pain.

_Don't push them!_ I scold. _You'll only wear yourself out more._

_He's coming!_ Toketsu Yoru gasps. _To check on you! Wake up, hurry!_

Aizen is coming to check on me? Could this day get any stranger? But I leave Toketsu Yoru, not wanting to be out of it when Aizen gets here. He enters my room and grins maliciously at me.

"So, did you figure out what I did?" he asks.

"N-no," I whimper.

"That person who was here," Aizen says, "Is not a Soul Reaper." My eyes widen in surprise. "He is an Arrancar. What I did was plant his power in Toketsu Yoru. You can use his Resurrection Form if you train hard enough." I gasp in shock. I know about Arrancars and Resurrection Forms. I also know what Aizen is planning with them. "This is what I've wanted to do all along. I've created a Soul Reaper through tests that can use an Arrancar's Resurrection Form, and she'll do what I want her to. You're part of my plan, Hoshiko. You _will_ attack Soul Reapers on the day that I attack Seireitei. That is an order."


	2. Chapter 2

**Brighty: Yay! We meet everyone now! I'm not using dialogue or exact character actions from the show cuz I forget it and don't feel like looking it up. Sorry!**

**Hoshiko: Brighty doesn't own Bleach, Tite Kubo does. She only takes credit for me**

Aizen takes me in for that "merging" test once more. The Arrancar is certainly a different one, but I still can't see them. I guess I'm not supposed to know who it is.

After the test, I rush to Toketsu Yoru to see what Aizen did to him this time. He was just barely used to the wings, and now Aizen throws something else at him. At least this test didn't leave him on the ground in agony. He was still in pain though.

_What did he do to you this time?_ I ask. _I don't see a really big difference._ He looks at me sadly and I let out a small shriek. His wolf-like yellow eyes have turned an almost ice-like shade of blue. I throw my arms around his neck in a comforting hug. _Can you see?_

_Yes, _he pants. _But not very well._

_Will you be okay if I leave?_ I ask. He gives me a questioning look. _Aizen said something about "making his move" today. I have to see what he means by that. He said he wanted me to fight, but I'm going to run. I can't do this anymore._ Toketsu Yoru nods in understanding. _I'll see you again soon._ And with that, I leave my inner world and get ready for today.

After a little while, Aizen comes in and grabs my arm. "You're going to watch first, Hoshiko, and then you will fight," he says. I nod. He doesn't really give me a choice, and I'm not going to show that I'm planning on going against him.

He leads me into a bright room. There are two other people in it. One of them is a girl bleeding badly on the floor, and the other is a smiling man with his eyes closed. A boy with white hair and green eyes rushes into the room and stares at the girl on the floor. "Momo!" the boy yells and runs towards the girl, only to be stopped by Aizen. "Aizen," the boy hisses, "I'm going to kill you! Bankai!" Ice shoots out of the hilt of the boy's sword, and covers his arm. Wings and a tail form from ice, and three purple flower type things float behind him.

"That's harsh, don't you think?" Aizen smirks, and the boy stabs him. I'm relieved, Aizen just got stabbed. But then I look closer and see Aizen standing behind the boy. What?

The boy suddenly starts bleeding badly, and falls to the floor. What did Aizen just do? How?

"Aizen!" a woman's voice yells. I see a woman with long brown hair braided down her chest and a girl with short silver hair next to her.

"Unohanna," Aizen acknowledges. "Hoshiko, attack her. I have no time." I look at him, horrified. How did he expect me to just attack this woman? "Hoshiko, now," he growls. I know by his tone that next time I make him say it he won't be so… _lenient_. I look at the woman apologetically before drawing my zanpaku-to and rushing towards her.

She draws her own and blocks my attack, but I have an idea. "Help me," I whisper softly, so softly I don't even know if she heard. She shunpos away from me, and sheathes her sword.

"What have you done to this poor girl, Aizen?" she asks. I'm relieved that I might get to leave.

"Just a few tests, nothing big," Aizen shrugs. That's when my patience snaps.

"Nothing big?" I challenge. "Nothing big? Not a single test went by where I wished that I could just die instead of bear that pain! What about Toketsu Yoru? You planted some sort of weird _wings_ on him! HE COULD BARELY MOVE! Then you went and changed his eyes before he was better! If we didn't converse in open tundra, he could have gotten seriously hurt! HE COULDN'T SEE! He still can't!" I feel I'm doing well. As long as he doesn't bring up a certain topic I'll be fine.

"I gave you power," he says calmly. "Your sword will heal given time, and when that time comes you will be at least as strong as a captain."

"Maybe," I snarl, "But I won't fight for you." I think it's the woman there who's giving me the courage to stand up to him. Boy, how long I have wanted to do this, to try to get away from him.

"Have you forgotten that I saved your life?" Aizen asks. Dammit! He brought it up!

"If I had known then that this is what would happen to me if I lived, I would've just let that Hollow kill me," I growl. Aizen calmly walks up to me and smacks me. I look him in the eye defiantly.

"What was that?" he growls. I've done it. I've ticked him off. In self-defense, I kick his knee, which makes his leg buckle, and run to the woman as fast as I can. She catches me in her arms and moves me behind her protectively.

"Isane, let everyone else know what's happened here, then get Lieutenant Hinamori, Captain Hitsugaya, and this girl out of here," the woman says. The girl nods and does some sort of kidou. Then she picks up the boy and motions for me to pick up the girl. I listen to her and follow her out. I can here Aizen freaking out behind me, probably because he lost his _precious test subject_. Boo hoo for him.


	3. Chapter 3

**Brighty: Sorry if they've been short… they will get longer, I promise**

**Hoshiko: Brighty doesn't own Bleach…**

It's been almost a week since then. The woman's name is Captain Unohanna, and she's a healer. The boy left a few days ago, being fully healed. I had no where to go to, so I stayed here.

"Hoshiko?" Unohanna asks. She walks into my room. "Come on. The Head Captain's going to put you in a squad." I nod and follow her out. I have no things to bring, because I don't have anything except Toketsu Yoru.

When I get to the meeting, all of the captains introduce themselves. "Now," Yamamoto starts, "We will place Hoshiko Tsukino in a squad. Does anyone have any objections?"

"Look at that thing strapped to her leg," the one who introduced himself as Captain Zaraki snorts, "How can you even call that a zanpaku-to?" I cringe at his words. Okay, so Toketsu Yoru looks a bit different from other zanpaku-tos. I keep him strapped to my right thigh, which I find very convenient. The hilt reaches up to my hips, and the tip of the blade doesn't even reach my knee.

"He's a little short, so what?" I challenge. I know it's not the best idea to challenge a captain on my first day, but I can't let him insult my best friend. "He fights just fine, as do I."

"Is that so?" Zaraki asks. "Then how about we place you based on your fighting skills?"

"A fight?" Unohanna exclaims. "She's not in any condition for that!"

"She'll be fine," Zaraki argues. "I'll send in my 5th seat."

"5th seat to start with?" the boy from earlier, Captain Hitsugaya, asks. "Isn't that a little too much?"

"I approve of the fighting assessment," Yamamoto concludes. "11th Squad's 5th seat, Yumichika Ayasegawa, will be her opponent. We will meet in the Squad 10 training grounds in one hour."

"But, Head Captain-" Unohanna starts.

"That decision is final," Yamamoto interrupts. I bow my head in acceptance and let Unohanna lead me away. Ukitake offered to come with us, but Unohanna politely refused. I think it's because I'm still a little uncertain around everyone except her. I wish I was being put in her squad.

Over the next hour, Unohanna gives me a tour around Seireitei on our way to the Squad 10 Training Grounds. Toketsu Yoru gets quite a few strange looks, but I ignore them. There's no reason for me to get worked up over that right before a fight.

When we get to the training grounds, Unohanna introduces me to Yumichika. He definitely looks… _odd_. He has freakin feathers on his eyelashes! That's not normal. But I don't say anything.

"Begin!" Yamamoto commands, and Yumichika charges at me incredibly fast. I barely have enough time to snatch Toketsu Yoru out of his sheath and block the attack. Now _this _is the advantage for having my sword being short. I only need one hand. The other hand can be used for balance, kidou, punching, anything that I would need it for.

I push him away with my blade and slash at him. He dodges easily, but I keep slashing, purposely keeping him on the defensive. He doesn't attack, I don't get hurt. That's what I fight by.

"Bloom, Fuji Kujaku," he commands. Now I'm in trouble. I don't want to release my shikai. I mean, I don't _want_ to kill him! Toketsu Yoru is very difficult to hold back with. Yeah, killing him would be bad.

His blade splits into four, all coming out of the same hilt. Oh great, just what I need. _More opposing weapons._ This was definitely not going to end well for me.

"Come on, girl!" Zaraki yells from the side. "You have a shikai don't you? Show it to us!" Is he serious? Does he seriously _want _his 5th seat to die? But then again, they don't know what my shikai does. Maybe I could just use it for a second, and then deactivate it before it does any real damage.

Yumichika starts putting me on the defensive, his attacks getting harder and harder to evade or block. I've had it. One second, that's it.

"Freeze, Toketsu Yoru!" I command. My zanpaku-to, hilt and all, bursts into shadow and disperses. I send the jet-black mist-like shadow towards Yumichika, and it engulfs him. I pull it back as soon as I can, but it still did major damage.

"Damn!" I mutter. "I overdid it!" Yumichika is on his knees, his lips are blue and he looks like he's on the verge of catching frostbite. "Dammit!" I say a little louder.

"Now what was that?" Zaraki asks. I sheathe my zanpaku-to.

"Toketsu Yoru," I say. "Frozen night. When activated, it turns into a small patch of "nighttime" that I can control. This shadow freezes anything and everything it touches, be it moisture in the air or the liquid in and on a body." I reach my hand out to Yumichika. "You okay?" I ask.

Yumichika nods and lets me help him up. "So…cold," he mutters. Instantly I feel bad. Why did I have to overdo it? I was being stupid, that's why. I should have just stuck with kidou.

"Just keep your room really warm tonight," I told him. "That takes care of it."

"Are you sure that's it?" Unohanna asks. "He looks like he needs immediate attention."

I shake my head. "It's not as bad as it looks. A warm night is all he needs. Trust me, I got myself during training once. Hell yeah, it felt horrible, but it doesn't take much to get rid of. A few more seconds and it could have been critical, though." Yumichika looks relieved that he only got a small bit of it.

"I have concluded that Hoshiko Tsukino will be placed in Squad 10," Yamamoto says. I look towards Squad 10s captain warily. The fact that he's a kid makes him a whole lot scarier, seeing that he's a captain at his age.

"Pleased to meet you," he says when I walk up to him.

"The pleasure is mine," I reply, bowing my head. As he leads me towards the barracks, I cast Unohanna a nervous glance. She nods encouragingly. I can hear Kurotsuchi arguing with Yamamoto behind us. Something about "Aizen's lab rat" and "See what he did". I think that he wants to put me through more testing to see exactly what Aizen did to me. I don't want to do that anymore.

When we reach where my room is, a blonde woman with big breasts runs up to Hitsugaya. "Well? Well?" she asks enthusiastically.

"Meet our newest squad member," he replies coolly. "Hoshiko Tsukino." I bow my head in greeting.

"So this is her?" the woman asks, analyzing me. Her gaze lingers on Toketsu Yoru but she doesn't say anything, "I'm Rangiku Matsumoto, the Lieutenant of Squad 10!" she says smiling. She holds out her hand and I shake it. "Well come on!" She grabs my hand and drags me into my room. I squeak in surprise.

Matsumoto helps me find everything I need, and helps me get ready for bed. I am beat after my fight. "Just let me know if you need anything," she says. I nod and she leaves. I flop down on my bed and think about what happened over the past week. A lot has changed.

I can hear Hitsugaya and Matsumoto talking outside of my room.

"Captain, are you sure she's safe?" Matsumoto asks. "In both terms, for us and for her."

"She is," Hitsugaya replies. "We just need to be wary of Squad 12 for the time being. Kurotsuchi seemed to be very interested in her. The last thing she needs right now is more testing."

"Yes, but can we trust her?" Matsumoto counters.

"Unohanna and the Head Captain both have high hopes for her, especially Unohanna. I believe she can be trusted," Hitsugaya says.

"I hope you're right about her, Captain," Matsumoto says before I hear her footsteps walking away. I can make out Hitsugaya's footsteps walking in the other direction.

He cares about me. Captain Hitsugaya wants to protect me from more tests. I feel strangely safe as I fall asleep in my new home.

**A/N: I probably should have made this clear before, but this story is going to only be the Aizen plot. I'll probably make other stories for the zanpaku-to rebellion, bount, etc.**


End file.
